Rick, I think that the statement made must be taken to mean what it says only within the context of it being an official national flag.
One can be sued for making and selling our traditional flag without consent.
However, if the Australian government wants to hold the copyright to the Aboriginal flag, it can compulsorily acquire it, but must pay "just compensation" to the owner in accordance with the Federal Constitution (the "Castle" principle"). S.51, IIRC.